1. Technical Field
This invention relates to communications switching systems, and particularly to the use of a computer for controlling the operation of a telephony system, such use is known in the art as computer telephony integration (CTI), and the systems employing such control are known as CTI systems.
2. Related Art
As a general background, the reader will find examples of such CTI systems disclosed in the articles “Introduction to Computer Telephony Integration”, by A. Catchpole, G. Crook, and D. Chesterman, British Telecommunications Engineering, Vol. 14, July 1995; “Computer Telephony Integration—The Meridian Norstar”, by A. Catchpole, British Telecommunications Engineering, Vol. 14, October 1995; “Computer Telephony Integration—The Meridian 1 PBX”, by P. Johnson, A. Catchpole, and L. Booton, British Telecommunications Engineering, Vol. 15, July 1996; “Callscape—Computer Telephony Integration for the Small Business”, by G. Hillson, G. Hardcastle, and M. Allington, British Telecommunications Engineering, Vol. 15, January 1997, and “Call Centres—Doing Business by Telephone” by M. Bonner, British Telecommunications Engineering, Vol. 13, July 1994.
Furthermore, a method is known of operating a CTI system comprising a CTI-enabled PBX, an associated CTI controller, and a plurality of user workstations, each workstation comprising a computer connected to the CTI controller and a telephone connected to the PBX In this method, the CTI controller stores respective user-associated profiles, each including a user-associated workgroup containing names of users of the system, in whose telephony status the user associated with that workgroup is interested, and the PBX on receipt of an incoming call retrieves from the signalling data a dialed number (known as the Dialed Number Identification Service number (DNIS)) and the calling line identity or identification (CLI), and passes these to the CTI controller. The CTI controller translates the DNIS to a username for the called user and accesses the workgroups to find out which contain that username. The CTI controller then sends a message containing that username to each computer at which a user, whose workgroup contains that username, is currently logged on to the CTI controller. It will be appreciated that in the art, the terms log on, logon, log in and login are synonymous and interchangeable, as are the terms log off, logoff, log out and logout.
While a user is currently logged on to the CTI controller, his computer displays a respective set of icons representing the members of that user's workgroup, the icons being in the form of respective facial images, each icon including a text display, e.g. “Free”, to indicate the current telephony status of the corresponding user, and upon receipt of this message, the computers change the text display of the icon corresponding to the received user name to “Ringing”. A user can answer an incoming call for a member of his workgroup by sending an answer message from his computer to the CTI controller, and the CTI controller responds by commanding the PBX to connect the incoming call to that user's telephone. This method is referred to as Distributed Office Telephony (DOT), and a specific embodiment of such a known system is disclosed in International Patent Publication Number WO 98/488557.